The non-adrenergic and non-cholinergic (NANC) inhibition has an important role in the intrinsic control of enteric nervous system (ENS). The ENS is poor in the upper digestive tract (esophagus and stomach) and totally present in the intestine. Starling and Bayliss experiments demonstrated the intrinsic activity of ENS in 1899. Since then there are searching for neurotransmitters of NANC like VIP (Vasoactive Intestinal Polypeptide) and ATP (Adenosine Triphosphate). Recent works demonstrate nitric oxide as a neurotransmitter of NANC. The nitric oxide (NO) is a gaseous molecule produced from L- arginine, with less than ten seconds half-life. The enzymes involved in the synthesis of NO are the NO synthases (NOS): neuronal NOS or isoform I, inducible NOS or isoform II, and endothelial NOS or isoform III. The isoform I and III are constitutive, and the isoform 11 is inducible. The mechanisms involved in the induction of isoform III are TNFα (Tumor Necrosis Factora), IL-Iβ (Interleukin I-β), and bacteria lypopolyssacarides stimulus. The intestinal smooth muscle motility is mediated by NANC and one example of this is the migratory motor complex (MMC). The MMC can be modified by infusion of NO-like drugs and this modification is reversed by infusion of L-NAME (L-arginine analog) in experimental trials with animals. The NO causes relaxation and inhibition of peristalsis in the small intestine. The adynamic ileum is a very common situation for surgeons. In the adynamic ileum is observed the dysfunction of MMC. The adynamic ileum induced by infusion of endotoxins is reverted by use of NOS inhibitors.